JAJSG65B September   2018  – December 2018 ADS1278-SP

PRODUCTION DATA.  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
    1.     Device Images
      1.      概略回路図
  4. 4 改訂履歴
  5. 5 概要（続き）
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Timing Requirements: SPI Format
    7. 7.7 Timing Requirements: Frame-Sync Format
    8. 7.8 Quality Conformance Inspection
    9. 7.9 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Sampling Aperture Matching
      2. 8.3.2  Frequency Response
        1. 8.3.2.1 High-Speed, Low-Power, And Low-Speed Modes
        2. 8.3.2.2 High-Resolution Mode
      3. 8.3.3  Phase Response
      4. 8.3.4  Settling Time
      5. 8.3.5  Data Format
      6. 8.3.6  Analog Inputs (AINP, AINN)
      7. 8.3.7  Voltage Reference Inputs (VREFP, VREFN)
      8. 8.3.8  Clock Input (CLK)
      9. 8.3.9  Mode Selection (MODE)
      10. 8.3.10 Synchronization (SYNC)
      11. 8.3.11 Power-Down (PWDN)
      12. 8.3.12 Format[2:0]
      13. 8.3.13 Serial Interface Protocols
      14. 8.3.14 SPI Serial Interface
        1. 8.3.14.1 SCLK
        2. 8.3.14.2 DRDY/FSYNC (SPI Format)
        3. 8.3.14.3 DOUT
        4. 8.3.14.4 DIN
      15. 8.3.15 Frame-Sync Serial Interface
        1. 8.3.15.1 SCLK
        2. 8.3.15.2 DRDY/FSYNC (Frame-Sync Format)
        3. 8.3.15.3 DOUT
        4. 8.3.15.4 DIN
      16. 8.3.16 DOUT Modes
        1. 8.3.16.1 TDM Mode
        2. 8.3.16.2 TDM Mode, Fixed-Position Data
        3. 8.3.16.3 TDM Mode, Dynamic Position Data
        4. 8.3.16.4 Discrete Data Output Mode
      17. 8.3.17 Daisy-Chaining
      18. 8.3.18 Modulator Output
      19. 8.3.19 Pin Test Using Test[1:0] Inputs
      20. 8.3.20 VCOM Output
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12デバイスおよびドキュメントのサポート
    1. 12.1 ドキュメントの更新通知を受け取る方法
    2. 12.2 コミュニティ・リソース
    3. 12.3 商標
    4. 12.4 静電気放電に関する注意事項
    5. 12.5 Glossary
  13. 13メカニカル、パッケージ、および注文情報

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

8.3.2.1 High-Speed, Low-Power, And Low-Speed Modes

The digital filter configuration is the same in High-Speed, Low-Power, and Low-Speed modes with the oversampling ratio set to 64. Figure 54 shows the frequency response in High-Speed, Low-Power, and Low-Speed modes normalized to fDATA. Figure 55 shows the passband ripple. The transition from passband to stop band is shown in Figure 56. The overall frequency response repeats at 64x multiples of the modulator frequency fMOD, as shown in Figure 57.

ADS1278-SP ai_frqresp-bas367.gifFigure 54. Frequency Response For High-Speed, Low-Power, And Low-Speed Modes
ADS1278-SP ai_passresp-bas367.gifFigure 55. Passband Response For High-Speed, Low-Power, And Low-Speed Modes
ADS1278-SP ai_transband-bas367.gifFigure 56. Transition Band Response For High-Speed, Low-Power, and Low-Speed Modes
ADS1278-SP ai_frqresp_fmod-bas367.gifFigure 57. Frequency Response Out To FMOD For High-Speed, Low-Power, And Low-Speed Modes

These image frequencies, if present in the signal and not externally filtered, will fold back (or alias) into the passband, causing errors. The stop band of the ADS1278-SP provides 100-dB attenuation of frequencies that begin just beyond the passband and continue out to fMOD. Placing an anti-aliasing, low-pass filter in front of the ADS1278-SP inputs is recommended to limit possible high-amplitude, out-of-band signals and noise. Often, a simple RC filter is sufficient. Table 2 lists the image rejection versus external filter order.

Table 2. Antialiasing Filter Order Image Rejection

ANTIALIASING FILTER ORDER IMAGE REJECTION (dB)
(f–3dB at fDATA)
HS, LP, LS HR
1 39 45
2 75 87
3 111 129